Abstract
Exocrine glands keep the cell polarity that is due to the tight junctions that partition a cell surface into apical and basolateral membranes. In the parotid gland, the transmembrane protein occludin is observed to form tight junctions along the intercellular canaliculi. Actin filaments run along the tight junction and aquaporin5 is specifically detected at the apical membrane. The polarity is important for oriented water and electrolyte transport. We have established a method to culture dispersed parotid acinar cells that retain their ability to generate new secretory granules and secrete amylase upon the stimulation. In this study, we analysed the cell polarity of the primary culture. After the culture for 24 h, since aquaporin5 was seen to have diffused to the plasma membrane, the apical membranes could not be distinguished. No occludin was detected, suggesting that the tight junction was broken in the primary culture. These results suggest that the polarity of the cells was lost. In contrast, at 48 h after the dispersion, the cells spread as a monolayer and occludin bands appeared again between the cells. Immunoblotting with anti-occludin antibody showed that the expression of occludin increased time-dependently although it was once lost after the dispersion. These results suggest that a kind of polarity may have begun to return. [Jpn J Physiol 55 Suppl:S72 (2005)]
